1. Field of the Invention
This invention pertains to devices used to lift concrete building or retaining wall blocks in position on a wall, and more particularly, to such devices that enable the blocks to be lifted directly from their pallets and easily repositioned for placement on the wall.
2. Description of the Related Art
Lifting devices that are attachable to backhoes to help construction workers more efficiently set heavy concrete blocks in place on building or retaining walls are widely known. These devices eliminate the need for workers to individually lift the concrete blocks off the pallets and position them on the wall, thus saving time, physical energy, and labor cost. Unfortunately, such devices are able to lift and position only one concrete block at a time, which makes wall building a slow, tedious process.
Large quantities of retaining wall blocks are transported from the supplier to the construction site on pallets. Occasionally, the blocks are aligned in layers that are stacked five to six layers high, with the blocks facing the same direction in each layer. Because each block typically weighs up to approximately 120 pounds, heavy equipment, such as a backhoe, is used to individually lift each block from the pallet. Once lifted from the pallet, the block is transported by workers for exact placement on the wall.
In order to expedite the process and reduce labor and equipment rental costs, a simple, inexpensive lifting device is needed that can easily and securely lift a plurality of blocks directly off the pallet for exact placement on the wall. What is also needed is such a lifting device that is relatively inexpensive to manufacture and easy to use.
It is an object of the present invention to provide a simple, relatively inexpensive, device that easily and securely lifts a plurality of concrete blocks using common construction lifting equipment, such as a backhoe.
It is another object of the present invention to provide such a device that lifts the concrete blocks in the original positions from a shipping pallet for immediate placement on the wall.
These and other objects of the invention which will become apparent are met by the lifting device disclosed herein designed to be used with a backhoe or crane to lift a plurality of blocks and then align them for exact placement on a wall. The device comprises a lifting bar that is suspended in a horizontally aligned position from a main cable or chain connected at its opposite end to the shovel or hook on a backhoe or crane. Extended downward from the lifting bar is at least one block lifting assembly designed to selectively attach to at least one of the vertically aligned holes formed on the block.
In the preferred embodiment, each block lifting assembly includes two long segments of chains or cables spaced apart and pivotally connected to the lifting bar. The lower ends of the long segments are spaced apart and pivotally connected to the upper corners of a rigid transfer plate. The upper ends of the long segments are sufficiently spaced apart on the lifting bar and the long segments are sufficient in length so that the transfer plate is aligned centrally over a block located on a pallet. Pivotally attached to the opposite lower corners of the transfer plate are two short segments of chains or cables. Pivotally attached to the opposite, lower end of each short segment is an elongated connecting rod. Each connecting rod is sufficient in diameter to slide into the vertically aligned hole formed on the block. In the preferred embodiment each connecting rod includes a plurality of outer ribs that press against the sides of the hole when the connecting rod is forced laterally to prevent its removal from the hole when the lifting bar is initially raised to lift the blocks. When the blocks are properly positioned on the wall, the lift bar is lowered so that the blocks rest on the wall and tension is relieved on the connecting rods so that they may be longitudinally aligned in the holes and able to slide freely to disengage from the hole.
In the preferred embodiment, the lifting device also includes an eye bolt or hook which connects to the main chain or cable attached to a backhoe or forklift that lifts the blocks to the wall.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. It should be understood, for example, that the two long segments could be replaced with one long segment centrally connected to the transfer plate. Also, the number of lifting assemblies attached to the lift bar is only limited by the length of the lift bar and the number of blocks on the pallet. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.